Screw driver



J. H. CONE 2,522,996

SCREW DRIVER Filed Feb. 6. 1945 INVENTOR 1 5g /1 H. 6077 BY W ATTORNEY5 Patented Sept. 19, 1950 SCREW DRIVER Joseph H. Cone, Bridgeport, Conn., assignor to Casco Products Corporation, Bridgeport, Conn., a corporation of Connecticut Application February 6, 1945, Serial No. 576,427

4 Claims. (01. 145- 50) This invention relates to screw drivers, and more particularly to a universal screw driver having bit means adapting it for use with either slotted or recessed screw heads.

1: An object of the invention is to provide a universal type screw driver adaptable to both slotted and recessed screw heads, which has relatively few, economically-produceable parts, yet which is strong and sturdy for the purpose intended.

This is accomplished by the provision of a screw driver having a novel combination including a shank with a fiat blade for conventional slotted type screws, and an adapter bit having at one illustrated herein the adapter bit is in the form of a deep drawn metal cup the walls of which may be shaped to provide splines, and the shank of the screw driver above the. flat blade may be splined to correspond with the cup so that a strong driving connection is thereby provided in addition to that resulting from the nesting of of the blade. The bottom and adjacent side walls of the'cup are indented in such a manner that, in addition to nesting the blade they provide a polyhedral-shaped tip, which may be substantially cruciform in section to correspond to the shape of cruciform-recessed screw heads.

By suitable hardening of the bit subsequent to its forming, a sturdy and tough structure may be obtained which readily withstands thestresses encountered during normal use, with a substantial factor of safety.

The polyhedral tip may have various shapes, to

conform to the various sizes and styles of recessed-head screws, without departing from the a spirit of the invention, two different sizes, of

cruciform section, bein shown in thedrawings.

A substantial area of contact is provided between the splined portions of the shank and bit to prevent the possibility ofshearing or splitting occurring at these points, and by the provision of an embossed nib on the bit, cooperating with a recessin the shank, a simple and effective detent action is provided, to retain the bit on the shank against accidental dislodgement therefrom.

Other features and advantages will hereinafter appear.

, In the accompanying drawings:

Figure 1 is a side elevation of a screw driver with an adapter bit, made according to the present invention.

Fig. 2 is an enlarged fragmentar View showing the screw driver applied to a recessed-head screw, the adapter bit being shown in section.

Fig. 3 is an elevation looking at the open end of the adapter bit, enlarged.

Fig. 4 is a side elevation of the bit, enlarged, a portion being shown in section taken on the line 44 of Fig. 3.

Fig. 5 is a section taken on the line 55 of Fig. 2. i

Fig. 6 is a bottom or tip view of the bit pictured in Fig. 4.

Fig. 7 is a fragmentary elevation of the blade end of the screw driver shank, with the adapter bit removed, and

Fig. 8 is a side elevation similar to Fig. l but showing a bit of a different size and shape, for use with the smaller sizes of recessed-head screws.

As shown in Fig. 1 the screw driver of this invention comprises in general a handle Ill which may be of any conventional shape and to which is secured a shank l I in the usual manner, a ferrule I2 of the conventional type being provided at the mouth of the handle. a

The portion l3 of the shank H which extends from the ferrule l2 may have any suitable crosssectional shape desired, although at present a round or cylindrical shank is preferred. Referringto Fig. 7 the shank H at its lower end is provided with an integral portion M of reduced diameter terminating in a fiat screw driver blade I 5, a shoulder i5 being provided between the shank portions l3 and M for purposes to be hereinafter described. As may be seen in Figs. 1 and 7, the blade [5 may be of a shape suitable for use with the conventional slotted head type of screw, for driving or loosening the latter in the usual manner.

According to this invention, a novel adapter bit I! is provided to be mounted over the blade I5 and reduced portion M of the screw driver shank, and the latter are arranged to drivingly cooperate with the bit- 5.! so that the screw driver may be used with the various types of recessedhead screws, one such type having the cruciformshaped recess shown in Fig. 5. The adapter bit I l is provided at one end with a socket which may receive the blade i5 and reduced portion M of the shank l l, the other end of the bit having a polyhedral shape for engagement with the recessed screw head. The shape of the adapter bit I1 is such that it may be economically fabricated in the form of a deep-drawn sheet metal cup, by a number of sequential stamping and drawing operations which may be carriedout, for instance, in an eyelet machine.

According to the above combination but a single additional part, comprising the adapter bit H, is required to adapt the screw driver for use with either slotted-head or recessed-head screws, this part being economically produceable from inexpensive material in large production quantities.

Referring to Figs. 1 through 4, the bit l! is shown as comprising a tubular generally-cylindrical Wall or body portion it having at its open end a substantially circular edge or lip l9 and at its closed end an integral closure or bottom portion 29. As seen in Figs. 1 and 6, the bottom of the bit is indented at four equispaced points designated by the numerals 2| so that the resultin shape of the bottom, shown clearly in Figs. 5 and 6, is substantially cruciform inside and outside. The indentations 2i extend longitudinally along the body it, gradually diminishing in depth until they eventually merge at the points 22 (Fig. 4) with the outer surface of the body, the indentations thereby forming four feathers or blades 23 extending radially from the axis of the bit and spaced 90 degrees apart.

Referring to Figs. 1 and 2, the blades 23 taper in both depth and width as they approach the bottom portion 26 of the adapter bit, the depthwis taper being provided by shaping the edges 24 of the blades so that they converge or extend angularly toward the aXis of the bit. As seen in Fig. 1, the sides 25 of the blades are slightly concave. I have found that by properly forming the indentations 2| in the bottom and lower body portion of the adapter bit ll the outer surface of the closed end portion of the bit may be given a polyhedral shape so that it satisfactorily drivingly engages the recessed heads of screws, as w shown in Figs. 2, 4, and 5.

Referring to Figs. 2 and 5, the internal shape of the adapter bit at its lower indented portion is such that it may receive and nest the blade I 5 of th shank H in either of two positions, one at right angles to the other, so that the said blade drivingly engages the bit. It will be noted that the broad sides of the blade 15 are slightly concave so that they may follow the convexity of the interior walls of the blade portions 23 of the adapter bit. Thus when the bit ii is placed over the blade i5 and reduced shank portion M of the screw driver, a driving engagement is had which prevents turning or slippage of the bit relative to the shank l i.

To take care of the thrust between the adapter bit IT and the shank H, the edge IQ of the bit is made to engage the shoulder l6 of the shank as shown in Fig. 1, this thrust arrangement operating without causing distortion of the bit in any manner.

Also according to the present invention additional means are provided for keying or locking the bit ii to the shank H against turning. In the embodiment of the invention illustrated herein these means comprise splines formed in the body [8 of the bit and in the reduced portion I l of the shank. As shown in Fig. 3 the wall 58 of the bit is formed to provide four internal lengitudinally-extending splines or ribs 26, and the portion i l of the shank is provided with longitudinal grooves 27 adapted to slidably receive the ribs26. The ribs 26 are located alternately with respect to the blades 23 of the bit, and the grooves 21 correspondingly located in the shank ll so that the blade l5 may nest in the bit in either of two positions, in alignment with one pair of opposite blades 23. As seen in Figs. 1 and 7, the splined portions of the bit H and shank I! have substantial length so that considerable strength and rigidity results, thereby preventing shearing, cracking or other failure of the assembled bit and the shank during use.

For the purpose of yieldably holding the bit I! on the shank portion !4 the latter is provided with depressions 28 in the surfaces thereof, and the wall l3 of the bit is embossed to provide an inwardly-extending protuberance 29 for cooperation with one of the recesses 28. The resiliency of the wall I 8 and the height of the protuberance 29 is such that a smooth yet firm detent action is thereby obtained.

After being formed to the desired shape, the adapter bit I! maybe suitably hardened and annealed to provide the requisite hardness and toughness.

It should be noted that the screw-engaging portion of the bit I! may have various shapes to fit various styles of recessed heads, the cruciform shape illustrated being shown by way of example. In Fig. 8 an adapter bit 30 is illustrated having a head-engaging tip 3! which is more pointed than the tip of the bit l1, andadapted for use with the smaller sizes of recessed heads.

For the purpose of conveniently storing the bits I7 and 30 when not in use, the handle H) of the screw driver is provided with a bore 32, and the handle end 33 is made removable so that the bits may be carried within the handle.

Variations and modifications may be made within the scope of this invention and portions of the improvements may be used without others.

I claim:

1. An adapter bit for use with recessed-head screws, comprising a drawn metal cup to receive a screw driver blade, the closed end of the cup having indentations at a plurality of points to provide a cruciform-shaped bit portion for driving engagement with a recessed-head screw, and the interior walls of the cup at said indentations being in spaced relation and forming a nest of right-angle slots for receiving the blade for driving engagement therewith.

2. A'bit for a slip-on attachment to a fiat screw driver blade comprising a metal sleeve closed at one end and open at the other to receive a screw driver blade and form a driving connection therewith, the walls of the sleeve at the closed end of the sleeve having two pairs of indentations to form a cruciform screw-driving tip, said indentations projecting inwardly and disposed in spaced relation to accommodate a fiat screw driver blade between them and form a driving connection therewith.

3. A screw driver comprising a shank having at its end a flat blade and a longitudinally extending spline adjacent the latter; and an adapter bit comprising a metal sleeve closed at one end and open at the other to receive the flat blade, the walls of the sleeve at the closed end of the sleeve having two pairs of indentations to form a cruciform screw-driving tip, said indentations projecting inwardly and disposed in spaced relation to accommodate the flat screw driver blade between them and form a driving connection therewith, said socket being splined for driving cooperation with the spline of the shank whereby a double driving connection is effected between the shank and body.

4. The invention as defined in claim 3 in which the adapter bit comprises a drawn metal shell, in which a wall of the sleeve of the bit has an inwardly extended protuberance, and in which the said shank is provided with a depression for cooperation with the protuberance to yieldably hold the bit on the shank.

JOSEPH H. CONE.

REFERENCES CITED The following references are of recordin the file of this patent:

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